1. Field
The following description relates to a photo sensor and to a photo sensor module configuring a UV sensor using poly silicon formed on a semiconductor substrate, which minimizes size of a chip by forming a passive device processing sensing signal in a vertical direction with a UV sensor.
2. Description of Related Art
UV sensing has recently been incorporated in various portable products, such as, for example, smart phone and wearable devices, because of an increase in awareness of protecting people from UV exposure. Such products, which are equipped with a UV sensor, can signal alarm before an end-user harms his or her health during outdoor exercise by measuring accumulated UV exposure concentration. Moreover, a UV sensor in smart phones or wearable devices can operate functions such as, for example, proximity and motion control, and measure UV exposure concentration, heart rate, pulse frequency and blood oxygen level.
Silicon photo diode is generally used as a UV sensor. U.S. Pat. No. 8,071,946 (Multi-function light sensor, registered on Dec. 6, 2011, hereinafter referred to as ‘prior document’) to Kita (“Kita”) is an example of a UV sensor which uses silicon photo diode. Kita is incorporated herein in its entirety by reference in the same manner as when each cited document is separately and specifically incorporated or incorporated in its entirety.
Kita discloses a UV sensor manufactured based on a Silicon on Insulator (SOI) substrate structure. The UV sensor provides a SOI substrate 12 comprising a silicon oxide insulator film 16 and a silicon semiconductor layer 18 configured of single crystal silicon on a silicon substrate 14. An ultraviolet ray sensing UV sensor is formed on the silicon semiconductor layer 18 configuring the SOI substrate 12. A first photo diode and a second photo diode which sense other rays, are formed on a silicon substrate 14 to avoid overlap with a UV sensor. A silicon oxide insulator film separates a first photo diode, a second photo diode, and a UV sensor.
A UV sensor with the above-mentioned structure has some problem. A UV sensor is manufactured formed on a silicon semiconductor layer of a SOI substrate. Moreover, any active device or passive device to process sensing signal is not formed on a lower UV sensor.
This makes it difficult to reduce the size of an IC chip comprising a UV sensor and making it difficult to reduce the size of the smart phones or wearable devices smaller.
Demand for a UV sensor, which can detect UV with high sensitivity while reducing manufacturing cost is increasing. The UV sensors known in the art are not capable of high sensitivity sensing function and being cheaper than a SOI substrate.